Internal combustion engines exhaust apparatus



F. AGGSBURGER ET AL Nov. 26, 1957 INTERNAL COMBUSTION ENGINES EXHAUST APPARATUS Filed Nov. 29, 1952 FIG. 7

AND LUDh/IG- LAUQEIIDER ETERNAL QGMBUSTION ENGINES EXHAUST APPARATUS Franz Augsburger, Munich, and Ludwig Lauhender, Traunstein, Germany, assignors to Firma Krauss-Maffei Aktiengeseiischaft, Munich-Allach, Germany Application November 29, 1952, Serial No. 323,325

Claims priority, appiication Germany December 6, 1951 6 Claims. (Cl. 60-29) In two-stroke multi-cylinder internal combustion engines having port scavenging, the outlet ports are first opened by the downwardly travelling piston, whereafter the scavenging ports are opened. Since each cylinder fires once for one rotation of the crank, the firing intervals, measured in crank degrees, amount to, for example, 90 degrees, in a four-cylinder engine. The duration of the opening of the outlet ports, also measured in crank degrees, amounts to 120 degrees and more. Consequently, the opening periods of the outlet ports of two cylinders following one another in the firing sequence overlap. If, for example, in a four-cylinder two-stroke diesel engine having two rows of cylinders arranged in V-formation with respect to one another the cylinders of a row which do not fire successively are connected to a separate exhaust pipe and the exhaust pipes of the two rows of cylinders converge into a common exhaust tail pipe. the pressure of the highly compressed exhaust gases of a cylinder having a straight exhaust outlet duct can consequently be propagated into the next firing cylinder connected to a different exhaust pipe while this cylinder is undergoing a change of charge and can thus interfere with the scavenging operation of the said latter cylinder, since the exhaust ports thereof are open at this instant. Even in the case of six-cylinder engines having rows of cylinders in V-formation, in which the firing intervals may amount to 30, 60 or 90 degrees and in which the opening duration of the outlet ports also amounts to 120 degrees, the scavenging operation in a cylinder is similarly impaired by the transfer of the exhaust pressure from another cylinder. The same conditions similarly exist in valve-controlled two-stroke multi-cylinder internal combustion engines.

In order to introduce the exhaust gases alternately flowing from one cylinder of the two cylinder rows into the common exhaust tail pipe, there may be arranged transversely above the engine an exhaust manifold or silencer into which the exhaust elbows of the engine lead either directly or through short exhaust pipes. However, this arrangement has the disadvantage that the overall height of the engine unit is considerably increased, and additional space is required to fit it into the vehicle, especially in the case of an engine disposed at the rear or under the floor, whereby the space for the accommodation of passengers is reduced. Moreover, the overflow of exhaust gases is facilitated by the relatively short distance between the cylinders of one row from those of the other row. It is therefore necessary to arrange the exhaust manifold below or at the side of the engine. More particularly, the lateral arrangement results in the exhaust pipes which lead from the engine to the exhaust manifold being of unequal length. Moreover, the vibrations set up between the engine and the exhaust manifold rigidly mounted on the frame, or the exhaust pipe rigidly mounted on the frame, produce fatigue phenom ena in the material, which result in leaks at the connecting joints, whereby the applicability of the exhaust arrangement is impaired.

7 rates it 2,814,178 Patented Nov. 26, 1957 The invention therefore has for its object to provide an exhaust arrangement which is economical in every respect and which in addition is so arranged and constructed that the vibrations and oscillations produced by the running engine can be harmlessly taken up by the exhaust arrangement, in order to avoid transfer of the pressure of the exhaust gases without an ejector. The steps for achieving this object reside in that the exhaust pipes are so constructed as to form a reinforcement of the frame and are yieldably connected to the resiliently mounted engine and so separately led into the exhaust manifold or silencer that the exhaust gases flowing from one exhaust pipe into the exhaust manifold are expanded to such an extent in the said exhaust box that the pressure thereof cannot be propagated into another exhaust pipe, a cylinder of which is in the process of being scavenged. The exhaust manifold is so arranged in the frame that the exhaust pipes leading into it are axially offset in relation to one another and also lead into the exhaust manifold at different angles in relation to the longitudinal axis of the said exhaust manifold. For the purpose of the frame connection, the exhaust pipe of the cylinder row lying opposite the exhaust manifold is arranged transversely to the frame and is connected thereto by welding, screwing, riveting or the like. The exhaust pipes consist of two or more tubular sections, the first of which is rigidly connected to the exhaust elbow at the engine and the last of which is connected to the frame or to the exhaust manifold, and which are connected together or to intermediate elements by yieldable means, for example by expansion joints, bellowstype tubes or the like.

In contrast to the known constructions, these steps provide an exhaust arrangement which not only avoids impairment of the performance of the engine due to depositions, even during lengthy operation, but is also insensitive to the shocks and oscillations set up, comprises no parts requiring maintenance and at the same time serves as a frame connection, whereby a further saving in weight and installation costs is effected.

A multi-cylinder internal combustion engine comprising an exhaust arrangement constructed in accordance with the invention is shown in elevation (Figure l) and in plan view (Figure 2) in the drawings.

The V-type two-stroke Diesel engine 1 serving to drive a vehicle is mounted in known manner on longitudinal bearers of the vehicle chassis 2. Connected to the exhaust manifolds 3 of each row of cylinders are the exhaust pipes 4, 5 consisting of a number of tubular sections, the first of which is rigidly connected to the exhaust manifold 3 at the engine 1 and the last of which is rigidly connected to the muffler 7 and which are connected together or to the intermediate sections by yieldable means, for example by expansion joints 6, bellows-type tubes or the like. Arranged on the outside of the left-hand longitudinal bearer of the frame, as seen in the direction of travel, is an exhaust muffier 7 serving as an expansion chamber, into which the exhaust pipes 4-, 5 lead. While the exhaust pipe 5 on the left leads to the exhaust mufiier 7 by the shortest path and opens into the forward end of the cylindrical casing, the right-hand exhaust pipe 4 first extends downwardly on the outside of the righthand longitudinal bearer of the frame and thereafter transversely below the vehicle frame towards the left-hand side of the latter. From here, it leads to that outer side of the exhaust muffler 7 which is remote from the engine and into the said manifold obliquely in relation to the longitudinal axis thereof, the point of introduction lying immediately behind that of the left-hand exhaust pipe 5. The exhaust tail pipe 8 is connected to the rear end of the expansion casing of the exhaust manifold 7 obliquely in relation to the direction of travel. That part of the right-hand exhaust pipe 4 which extends transversely below the vehicle frame is rigidly connected to the longitudinal bearers 2 of the frame and serves as a transverse frame connection, the exhaust pipe being secured by retaining plates 9 which are connected on the one hand to the exhaust pipe 4 by welding and on the other hand to the vehicle frame 2, by riveting, screwing or the like. Thus the transverse frame connection usually required at this point can be dispensed with.

The exhaust manifold 7 may alternatively be arranged transversely above or below the vehicle frame 2 and so constructed as to provide a reinforcement for the frame, whereby the further advantage is obtained that the exhaust pipes 4, 5, which in this case are introduced into the ends of the exhaust manifold are equal or substantially equal in length.

As soon as the exhaust ports are opened in the downstroke of the working piston in the cylinder of the Diesel engine, the exhaust gases under high pressure flow through the exhaust pipes 4, 5 into the exhaust mufller 7 and thereafter through the exhaust tail pipe 8 into the atmosphere. Due to the sudden widening of the cross-sectional area of throughflow in the exhaust muflier 7, a considerable expansion of the exhaust gases from a cylinder discharging straight into the exhaust muffler 7 occurs, so that the pressure of the exhaust gases cannot be propagated through the other exhaust pipe into a cylinder which is in the process of being scavenged, and thus interfere with the scavenging operation. The exhaust muffler 7 thus serves as a pressure reducer, its action being assisted by the oblique introduction and by the fact that the exhaust tubes 4, 5 leading into the exhaust manifold are offset in relation to one another.

We claim:

1. An exhaust system for a multi-cylinder two-stroke combustion engine and comprising, in combination, an elongated expansion vessel having a logitudinal axis and an outlet, said expansion vessel being located at one side of the engine; a pair of exhaust manifolds located on opposite sides of the engine and adapted to communicate with non-successively firing cylinders of the same; a pair of exhaust pipes respectively connected to said manifolds and having pipe end portions connected to and communicating with said expansion vessel, the exhaust pipe connected to the exhaust manifold located at said one side of the engine and at the same side as said expansion vessel being shorter than the other exhaust pipe, said pipe end portions extending at different angles to the axis of said expansion vessel and being inclined to the axis of said expansion vessel, the angle defined by said pipe end portion of said shorter exhaust pipe with the axis of said expansion vessel being greater than the angle defined by the other pipe end portion with said axis of said expansion vessel so that the streams of exhaust gases passing from said exhaust pipes into said expansion vesel move along different paths.

2. An exhaust system for a multi-cylinder two-stroke combustion engine and comprising, in combination, an elongated expansion vessel having a logitudinal axis and an outlet at one end thereof, said expansion vessel being located at one side of the engine; a pair of exhaust manifolds located on opposite sides of the engine and adapted to communicate with non-successively firing cylinders of the same; a pair of exhaust pipes respectively connected to said manifolds and having pipe end portions connected to the other end of said expansion vessel and communicating with said expansion vessel, the exhaust pipe connected to the exhaust manifold located at said one side of the engine and at the same side as said expansion vessel being shorter than the other exhaust pipe, said pipe end portions extending at different angles to the axis of said expansion vessel and being inclined to the axis of said expansion vessel, the angle defined by said pipe end portion of said shorter exhaust pipe with the axis of said expansion vessel being greater than the angle defined by the other pipe end portion with said axis of said expansion vessel, said pipe end portion of said shorter exhaust pipe being spaced from said outlet in said expansion vessel a greater distance than said pipe end portion of the other exhaust pipe so that the streams of exhaust gases passing from said exhaust pipes into said expansion vessel move along different paths.

3. An exhaust system for a multi-cylinder two-stroke combustion engine and comprising, in combination, a pair of exhaust manifolds located on opposite sides of the engine and adapted to communicate with non-successively firing cylinders of the same; an elongated expansion vessel having an axis and an outlet at one end thereof, said expansion vessel being arranged at one side of the engine and being spaced from one of said exhaust manifolds a shorter distance than from the other of said exhaust manifolds; a first exhaust pipe connecting said one exhaust manifold with said expansion vessel and having a first pipe end portion communicating with said expansion vessel and being inclined to the axis of the same, said first pipe end portion extending at a first angle with respect to said axis; a second exhaust pipe including one end portion connected to the other exhaust manifold and extending substantially symmetrical to said first exhaust pipe, an intermediate portion extending from said other side of the engine to said one side of the same, and a second pipe end portion communicating with said expansion vessel, said second pipe end portion being inclined to the axis of said expansion vessel and extending at a second angle with respect to said axis, said second angle being smaller than said first angle, said first and second pipe end portions opening into said expansion vessel at points located at the other end of the same so that the exhaust gases move in said expansion vessel along different paths toward said outlet.

4. An exhaust system for a multi-cylinder two-stroke combustion engine and comprising, in combination, a pair of exhaust manifolds located on opposite sides of the engine and adapted to communicate with non-successively firing cylinders of the same; an elongated expansion vessel having an axis and an outlet at one end thereof, said expansion vessel being arranged at one side of the engine and being spaced from one of said exhaust manifolds a shorter distance than from the other of said exhaust manifolds; a first exhaust pipe connecting said one exhaust manifold with said expansion vessel and having a first pipe end portion communicating with said expansion vessel and being inclined to the axis of the same, said first pipe end portion extending at a first angle with respect to said axis; a second exhaust pipe including one end portion connected to the other exhaust manifold and extending substantially symmetrical to said first exhaust pipe, an intermediate portion extending from said other side of the engine to said one side of the same, and a second pipe end portion communicating with said expansion vessel, said second pipe end portion being inclined to the axis of said expansion vessel and extending at a second angle with respect to said axis, said second angle being smaller than said first angle, said first and second pipe end portions opening into said expansion vessel at points located at the other end of the same, the point at which said first pipe end portion opens into said expansion vessel being spaced from said outlet of the same a greater distance than the point at which said second pipe end portion opens into said expansion vessel so that the exhaust gases move in said expansion vessel along different paths toward said outlet.

5. An engine suspension and exhaust system comprising, in combination, a pair of substantially horizontal parallel frame members; a combustion engine supported on said frame members; a pair of exhaust manifolds located on opposite sides of the upper portion of said engine and having a pair of outlet ends located at one end of said engine; an elongated mufiler located at one side and adjacent the lower part of said engine, said muffler extending substantially parallel to said frame members and having one end substantially located in a plane transverse to said frame members passing through said outlet ends of said exhaust manifolds; a first exhaust pipe located in said plane and connecting the outlet end of the manifold located at the same side as said muffler with said one end of said muffler; and a second exhaust pipe located in said plane and including a first pipe section connected to the outlet end of the other manifold and extending substantially symmetrical to said first exhaust pipe, a second intermediate pipe section extending transversely to said frame members and being rigidly secured to the same for bracing the same, and a third pipe section connected to said one end of said mufller.

6. An exhaust system for a multi-cylinder two-stroke combustion engine, comprising, in combination, an elongated expansion vessel having a longitudinal axis and an outlet; a pair of exhaust manifolds adapted to communicate with non-successively firing cylinders of the engine; a pair of exhaust pipes respectively connected to said manifolds and having pipe end portions connected to and communicating with said expansion vessel, one of said exhaust pipes being shorter than the other of said exhaust pipes, said pipe end portions extending at ditferent angles to said axis of said expansion vessel in such a manner that the angle defined by said pipe end portion of said shorter exhaust pipe with the axis of said expansion vessel is greater than the angle defined by the other pipe end portion with said axis of said expansion vessel so that the streams of exhaust gases passing from said exhaust pipes into said expansion vessel move along different paths and the stream of exhaust gases from said shorter exhaust pipe moves within said expansion vessel along a longer path than the stream of exhaust gases passing from said longer exhaust pipe into said expansion vessel.

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